Scanning the horizon: anticipating future changes in Portuguese aquatic ecosystems

We identified 15 emerging and poorly understood topics related to aquatic ecosystems in Portugal (from an initial pool of 43), which were scored and prioritized using a consensus-based Delphi technique. For marine ecosystems, the topics included current and future threats to low-lying sandy coasts, the impacts of the green energy transition, the risks posed by pathogens on floating ocean debris, the strategic importance of algae for a sustainable future, and Portugal’s potential contribution to the expansion of Marine Protected Areas. For freshwater ecosystems, the topics included identifying drought refuges for freshwater biodiversity, assessing the potential ecological and social costs of water highways, uncovering the hidden impacts of clean energy (floating solar panels and lithium mining), managing water quality in reservoirs, and understanding the potential impacts of the recent expansion of intensive olive orchards. For cross-cutting topics relevant to both types of ecosystems, the most scored topics included the importance of aquatic super-sites for ecological monitoring, new solutions for detecting and removing emerging pollutants, the application of rewilding, the impact of forest pathogens and emerging zoonoses, and the rise of organic compounds as a multidimensional threat. Prioritizing these topics can support a more proactive approach to conserving, managing, and sustainably exploring aquatic ecosystems in Portugal. This methodology can also be used to prioritize research funding areas identified bottom up (by the scientific community) rather than dictated from the top down (by decision-makers) and serve as a roadmap for conducting similar exercises in other regions of the world.